Parallel ruler and method of making the same



J. NASH April 6, 1948.

PARALLEL RULER AND METHOD OF MAKING THE SAME Fild 'Sept. 2, 1944 INVENTOR.

ATTORNEY James Nash Patented Apr. 6, 1948 PARALLEL RULER AND METHOD OF MAKING THE SAME James Nash, Milwaukee, Wis., assignor to Eclipse Moulded Products Company, Milwaukee, Wis., a corporation of Wisconsin f Application September 2, 1944, Serial No. 552,427

I 7 Claims. l

This invention relates to "parallel rulers and method of making thesame.

One object of the presentinvention is to provide a parallel ruler which has the blades and links molded to the proper shape and dimensions to eliminate costly machining thereof.

Another object is to provide a parallel ruler in which the blades and links are molded with apertures to receive the pivotal connections.

Another object of the invention is to provide an inexpensive method of making a parallel ruler.

Another object is to provide a parallel ruler with pivotal connections that maintain the level position of the links and prevent radial movement of each link.

A further object is to provide a parallel ruler having freely floating links and blades without loss of accuracy. I

Another object is to provide a resilient connection between the links and blades.

Another objectis to provide a parallel ruler with pivotal connections that arefabricated from standard parts readily provided and of lowcost.

Another object isto provide pivotal connections between links and blades that self compensate for wear.

Another object is to provide a parallel ruler with pivotal connections in which'the rivet or the like merely serves to hold the links and blades together and not as a bearing member.

These and other objects ofthe invention appear hereinafter in connectidnwith the description of several embodiments" of the invention illustrated in the accompanying drawings.

In the drawings: l

Figure 1 is a top plan view ofa parallel ruler embodying the features of the invention;

Fig. 2 is an end view of the ruler;

Fig. 3 is a longitudinal side elevation of the ruler; i

Fig. 4 is a detail enlarged section taken through one of the pivotal connections between a link and blade and illustrating a joint that may be employed; I p

Fig. 5 is a section similar-to. Fig. 4and illustrating another form. of pivotal connection that may be utilized between a link and blade; and

Fig. 6 is a perspective view of the U bent sprin washer employed in each embodiment.

The parallel ruler of the invention comprises in general a pairof straight edge blades I and 2 of the same shape and dimensions having pivotal connections 3 and 4, and 5 andtrespectively, and joined together by a pair of links ,1 and 8 of equal length with link 1. extending from connection 3 of blade I to connectioni of blade 2 and link 8 extending from connection 4 of blade I to connection 6 of blade 2.

Both the blades and links are molded to the desired dimensions and shape from suitable plastic material in order to eliminate extensive machining operations and provide an inexpensive method of fabrication.

In the molding of blades l and 2 holes or apertures are provided in blade I at pivotal connections 3 and 4 and similar holes or apertures are provided in blade 2 at pivotal connections 5 and 6. The holes are enlarged in substantially the lower half of the blades to provided each hole with shoulder 9 at substantially the center of the blade thickness. I

Also in the molding of the blades knobs II] are molded integral with the upper surface thereof at suitable locations to facilitate manipulation of the blades.

The outer longitudinal working edge I I of each blade I and 2 is molded to slope downwardly from to top surface thereof to a straight vertical face portion I2 near the bottom surface of each blade to provide a good working edge. The inner edge I3 is molded with a straight vertical face so that the ruler may be readily closed with the blades disposed back to back. The outer vertical edges are also straight and after molding none of the edges need be machined.

The molding of links I and 8 is accomplished in much the same manner as the folding of blades I and 2 and each link is provided with a hole or aperture at the pivotal connection area to..be concentrically aligned with the holes in the blades upon assembly together.

After the molding operations have been completed links I and B and blades l and 2 are cleaned of molding flash to make them ready for assembly. No machining operations need be performed, except that it may be desirable to ream out the hole at pivotal connection 6 in blade 2 to align the hole with that at pivotal connection 5 and accurately space the same therefrom, and to insure that the distance between pivotal connections 5 and 6 of blade 2 is equal to the distance between pivotal connections 3 and 4 of blade I.

The pivotal connections that may be employed to resiliently join and circumferentially interlock the links and blades together are illustrated in Fig 4 and 5 of the drawings. Since all the connections are similar it is only necessary to refer to connection 4 forpurposes of description.

In the embodiment of the invention illustrated in Fig. 4, pivotal connection 4, in general, comprises a bearing member or grommet HI to sepaof pivotal connection 4 of blade I and tightly hugs the wall of the hole'finithe area above shoulder 9. The upper head I8of the grommet is outwardly curved'to rest on the top surface of blade encircling the pivotal connection hole.

The head It of grommet I4 separates blade i from link 8 when the latter is assembled there'- with is curved in cross section to seat in the annular grooveIB-eXtendin arOund the hole of 'ccnnection lronthe bottom-surface of link 8.

Groove I9 is formed afterthe molding of link 8; preferably .by-a hotdie pressing operation, and

has tapered side' walls'for'engaging and centering the'curved'head I8 of the grommet. Link t rides'cn'the curved head of grommet id and at no time contacts blade I. The receiving of grommet -or'circular bearingiseat HI: in circular groove 39 preventslateraljdifset of the link and blade 3 relativev to theaxis of the pivotal connection.

Rivet t5, joining the blade'and link together, ofstandard shape obtainable in, the commermarket-and has .a flanged head 2c which overliesthetopsurface of link 8. A resilient U bent metal washer I5 isdisposedbcneath head 26 and'separatesl the head from the link.

The stemor shank :Ofi rivet' I5 passes through the pivotal-connection hole of link 8 and grommet 64 disposed in the pivotal connection hole;

of blade I! The-lower :end of rivetv I5 is hollow to provide a 2| which, after assembly of the parts, is flared radially. :outward and up against the washer ll. 1

The rivet shank is preferably loose in both the .link'il andzsgrommet I4'butshould fit tightly in washer H.

The washer" I'If-fits tightly against shoulder 9 and substantiallytcenters the rivet in the hole. This construction ravoids any interference with the pivotal action 'ofrli-nk 8lby the rivet and provides that' the rivet-merely secures the parts together axially of the connection.

- In. assembling Ea "pivotal connection such as pivotal connectionflggrommet I4 is disposed in the hole of 'b1ade1I-with the'head of the grommet overlapping the top surface of the blade. Spring washer is is'thenslipped over the stem of rivet it into "contact withheadzn'and' the rivet is inserted in the aligned'pivotal connection holes of "connection l radialiylspacedfrom the walls of linkhand blade I.

1W asher I'Iis'neXt slipped "over the "end of the rivet stemprojecting from the' bottom of blade I 4 and which provides a bearing for the link to rotate thereon, The spring washer I6 beneath head 20 of rivet I5 keeps the grommet seated in the groove. The level of the link is thus always 5 maintained above the blades and the link floats freely with respect to the rivet which at no time serves asa bearing therefor.

.In another embodiment.:of;the invention illustrated in Fig. 5, washer I! of the embodiment of 'Fig. 4.- is eliminated and the spring washer I6 of Fig. 4 is substituted therefor. The remaining partsrof the'pivotal connection are preferably the sameas in Fig; 4. The transfer of washer I6 to the formeralocation of Washer I'I reduces the gnum-ber ofi' parts and makes it possible. to employ ;a: shorter rivet.

Theinvention provides an accurate and efiective para'l'le1"'ru1er""that is inexpensive to manuiacturai due to the method of fabrication by molding and through the utilization of pivotal I connections which are..,,provided byinexpensive standard parts.

The lateraL interlockbetween the blades and links atieach pivotaltconnection maintains the blades in accurate rparallel: relation at all times.

Various embodiments oflthe invention. may be employed Within the-scope of the accompanying claims. a

I claim:v 1 a W 1. In a, parallel.ruler-rhaving a pairof blade members and lin-k members;apivotal-connection between eachabladenandllink comprising, a rivet member loosely extending within I the concentrically alignedsholes ofla 'link and blade, means disposed between the blade and link members toseparate theisame.and-provide a bearing for one of saidvmembers and resilient means confined at one end of said rivet memberto maintain the respective'blade or link member to maintain the respect-iveblade-or-link member seated on said bearing means and. radially spaced from said rivet member. 1 2. In a. parallel ruler having .apairof blade members and link members, a-pivotal connection 7 between eachbladenand link comprising, a rivet member loosely extending within the concentrically aligned holes :of .acli-nk andblade, a bearing member-disposed between the blade and link member to-separate the.same,:said bearing member encirclingrthe .rivet-cnemberand having one end seatedin an annular -ygroove in the bottom .surface.ofL-thelinkaroundthe pivotal hole therethrough toprovide-avbearing forsaid linkyand resilient means confinedat one end of said rivet member to maintain the seatingof "the hearing holes for receiving pivotal connections therefor witheach" pivotal *connection Lcom'prising 1a rivet "disposed loosely in "the ra-ligned holes for "each pivotal connection to iisecure the parts :axially together, a, circular bearing seat secured in one of .said 'm-emberstiandiadapted to' space the other member-axially therefromxor tree-pivoting relative thereto,zanl'lra circularzgroove in said other member'for receivingF'saidl-bearing seat and preventing slat-era] dflsetting' of said member rela- 7 tive to 'the axis of the pivotal connection.

'4. A -parallel'irulercomprising a pair of blade "members *and'hnk rmembers -v'vith 'space'd holes to "receive pivotal connections fjoining the blades and links"togethermeachiof said' pivotal "connectionsi'comprisingi respectively arivet' member d-is- 5 posed within the concentrically aligned holes oi. a blade and link member and radially spaced from the walls of said members, a grommet disposed between the blade and link to separate the same, said grommet encircling said rivet within the blade member and being seated at the upper end thereof in an annular groove in the bottom surface of the link around the hole therethrough toprovide a bearing for said link, and resilient means confined at one end of the rivet to maintain the seating of the grommet in said groove and prevent lateral movement of said link.

5. A parallel ruler comprising a pair of blade members and link members with spaced holes to receive pivotal connections therefor with each connection comprising a rivet disposed within the concentrically aligned holes of a blade and link member and axially spaced from the walls of said members, a grommet disposed between the blade and link to separate the same, said grommet encircling said rivet within said blade and being seated at the upper end thereof in an annular groove in the bottom surface of the link around the hole therethrough to provide a bearing for said link, a resilient member encircling the upper end of the rivet above the link to maintain the seating of the grommet in said groove, and a washer encircling the lower end of the grommet, the lower end of said rivet being flared upwardly against said washer to secure the parts together.

6. The method of making a parallel ruler which comprises providing a pair of blade members and a pair of link members for joining said blade members in parallel relation, pivotally connecting the respective members in vertically spaced relation with the links mounted above the blades, and laterally interlocking the links and blades at each pivotal connection to prevent lateral dis placement of one member relative to another and maintain the blades in accurate parallel relation at all times.

7. A parallel ruler comprising a pair of blade members and link members, respectively, pivotal connections joining the link members and blade members, a centering interlock spacing the links axiall from the blades at the corresponding pivotal connections and preventing lateral offset of the links and blades relative to the axis of the pivotal connections, a rivet passing through said centering interlock and adjacent members to secure the same together, and resilient means confined around each pivotal connection to maintain the centering interlock between the blades and links.

JAMES NASH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent N 0. 2,439,346: April 6, 1948.

JAMES NASH It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 2, line 32, for the word folding read molding; column 4, lines 39 and 40, claim 1, strike out to maintain the respective blade or link member; line 55, claim 2, for the word hearing read bearing; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 1st day of June, A. D. 1948.

THOMAS F. MURPHY,

Am'atzmt Oomaiesiomr of Patents. 

